Pressure transducers, for example a Pirani gauge or equivalent, are commonly used to measure gas pressure within enclosed environments (for example, processing chambers, areas between the pump and the process chamber, or load locks). Typically, the pressure transducer is contained within a housing that is positioned externally relative to the enclosure or chamber surrounding the environment. The pressure transducer housing is in communication with the enclosure by a conduit sealed therebetween. Consequently, the environment within the enclosure is extended to the pressure transducer via the conduit. The connecting conduit usually consists of a first fitting, secured to the pressure transducer housing, and a mating second fitting connected to the enclosure. Common methods of forming a gas tight seal between the pressure transducer housing and the fitting secured thereto include welding, soldering, brazing, bolting and the use of adhesives. Most of these methods require trained or skilled labor, as well as the use of tools for assembly.
The present invention provides a transducer assembly where a gas tight seal can be formed against a fitting without employing skilled labor or the use of tools. The transducer assembly includes a transducer member supporting a transducer element for measuring properties of an environment. The transducer member has a sealing surface surrounding the transducer element. A housing is included which has an integral resilient member for resiliently supporting the transducer member and for exerting a sealing force on the transducer member against a mating member secured to the housing.
In preferred embodiments, the transducer assembly is a pressure transducer assembly for measuring pressure. The transducer assembly further includes the mating member which consists of a fitting having a circular cavity therethrough for sealing against the sealing surface of the transducer member and for surrounding the transducer element. The fitting facilitates coupling of the transducer assembly to the environment. A locking arrangement on the housing locks the fitting to the housing. The locking arrangement includes an angled circular groove formed in the housing near the opening of the housing for engaging an angled circular locking flange extending from the fitting. A filter element is positioned within the fitting for protecting the transducer element from contaminants. The housing has an interior with a circular opening thereto and a resilient rear wall forming the resilient member. A protrusion extends from the resilient rear wall towards the opening of the housing and into contact with the transducer member for exerting the sealing force on the transducer member in an axial direction. The transducer member includes a rigid circular plate having first and second sides. The transducer element and an annular flange forming at least a portion of the sealing surface, extend along the first side of the plate. An xe2x80x9cOxe2x80x9d ring is positioned on the annular flange to provide further sealing between the transducer member and the fitting. A circuit board facing the second side of the plate is electrically connected to the transducer element. The circuit board has an opening therethrough so that the protrusion from the resilient rear wall is able to extend through the opening before contacting the rigid circular plate.
The present invention allows a fitting to be sealed to a pressure transducer member in a gas tight manner merely by pushing the fitting by hand into the opening of the housing which surrounds the pressure transducer member until the fitting locks to the housing. This saves labor and time during assembly which results in cost benefits as well as flexibility for inventory. For example, the pressure transducer assembly may be offered with a choice of fittings. The customer is able to request a particular fitting which is secured to the housing prior to shipment. Alternatively, since the assembly procedure is simple and easily conducted, this can also be performed by the customer.